Glass laminated products have contributed to society for almost a century. Beyond the well known, every day automotive safety glass used in windshields, laminated glass is used in windows for trains, airplanes, ships, and nearly every other mode of transportation. Safety glass is characterized by high impact and penetration resistance, and it does not scatter glass shards and debris when shattered.
Safety glass typically consists of a sandwich of two glass sheets or panels bonded together with an interlayer of a polymeric film or sheet. One or both of the glass sheets may be replaced with optically clear rigid polymeric sheets, such as sheets of polycarbonate materials. Safety glass has further evolved to include multiple layers of glass or rigid polymeric sheets bonded together with interlayers that may include one or more polymeric films or sheets.
The interlayer is typically made with a relatively thick polymeric film or sheet, which exhibits toughness and bondability to provide adhesion to the glass in the event of a crack or crash. Over the years, a wide variety of polymeric interlayers have been developed for use in safety glass. In general, these polymeric interlayers must possess a combination of characteristics including very high optical clarity, low haze, high impact resistance, high penetration resistance, excellent ultraviolet light resistance, good long term thermal stability, excellent adhesion to glass and other rigid polymeric sheets, low moisture absorption, high moisture resistance, and excellent long term weatherability. Widely used interlayer materials include complex, multicomponent compositions based on poly(vinyl butyral) (PVB), polyurethane (PU), poly(vinyl chloride) (PVC), metallocene-catalyzed linear low density polyethylenes (mPE or LLDPE), poly(ethylene-co-vinyl acetate) (EVA), polymeric fatty acid polyamides, polyesters (e.g., poly(ethylene terephthalate) (PET)), silicone elastomers, epoxy resins, elastomeric polycarbonates, and the like.
A more recent trend has been the use of glass laminated products in the construction business for homes and office structures. The use of architectural safety glass has expanded rapidly over the years as designers have incorporated more glass surfaces into buildings. In conjunction with this development, threat resistance has become an ever increasing requirement for architectural glass laminated products. Thus, newer safety glass products are designed to resist both natural and man made disasters. Examples of these needs include the recent developments of hurricane resistant glass, now mandated in hurricane susceptible areas, theft resistant glazings, and the more recent blast resistant glass laminated products. These products have great enough strength to resist intrusion even after the glass in the laminate has been broken, for example, the interlayer maintains its integrity against further insult when a glass laminate is subjected to high force winds and impacts of flying debris as occur in a hurricane or where there are repeated impacts on a window by a criminal attempting to break into a vehicle or structure.
In addition, glass laminated products have now reached the strength requirements for being incorporated as structural elements within buildings. An example of this would be glass staircases now being featured in many buildings.
Society continues to demand more functionality from laminated glass products beyond the strength and safety characteristics described above. One area of need is to reduce the energy consumption within the structure, such as an automobile or building, of which the laminated glass is a part. This need has been met through the development of solar control laminated glass structures. The solar energy strikes the earth over a wide spectral range of from 350 nm to 2,100 nm, with the maximum intensity found at 500 nm. The solar energy is divided into spectral regions, such as the ultraviolet region of 449 nm or less, the visible region of 450 nm to 749 nm and the near infrared region of 750 nm to 2,100 nm. The solar energy intensity distribution across these spectral regions is 4.44% for the ultraviolet region, 46.3% for the visible region and 49.22% for the near infrared region. Removing the energy from the visible region would sacrifice visual transparency through windows and, therefore, detract from the purpose for having windows. Since the near infrared region is not sensed by the human eye, however, typical solar control glass laminates have attempted to remove the energy from the near infrared region. For example, the air conditioning load in the summer may be reduced in buildings, automobiles and the like, which are equipped with solar control windows that prevent the transmission of near infrared radiation.
These solar control glass laminates may be obtained through modification of the glass or of the polymeric interlayer, through the addition of further solar control layers, or through combinations of these techniques.
A recent trend has been the use of metal oxide nanoparticles. These materials absorb the infrared light and convert the energy to heat. To preserve the clarity and transparency of the substrate, these materials need to have nominal particle sizes below about 50 nanometers (nm).
Infrared-absorbing nanoparticles which have attained commercial significance are antimony tin oxide (ATO) and indium tin oxide (ITO). These nanoparticles are typically produced through either a precipitation/calcination procedure or a flame pyrolysis process. Antimony tin oxide particles and indium tin oxide particles may be produced as disclosed within, e.g., U.S. Pat. No. 4,478,812; U.S. Pat. No. 4,937,148; U.S. Pat. No. 5,075,090; U.S. Pat. No. 5,376,308; U.S. Pat. No. 5,772,924; U.S. Pat. No. 5,807,511; U.S. Pat. No. 5,518,810; U.S. Pat. No. 5,622,750; U.S. Pat. No. 5,958,631; U.S. Pat. No. 6,051,166; and U.S. Pat. No. 6,533,966. These antimony tin oxide nanoparticles and indium tin oxide nanoparticles have been incorporated into polymeric interlayers of glass laminates or used to form solar control coatings on film substrates.
A more recent trend has been the use of metal boride nanoparticles, such as lanthanum hexaboride (LaB6). These materials also absorb the infrared light and convert the energy to heat. To preserve the clarity and transparency of the substrate, these materials need to have nominal particle sizes below about 200 nanometers (nm).
A shortcoming of solar control laminates which incorporate infrared absorptive materials is that a significant proportion of the light absorbed serves to generate heat, some of which radiates into the very structure that the solar control laminate was meant to protect. This is especially true for stationary structures, such as parked automobiles and buildings.
One development to produce solar control laminated glass is the inclusion of metallized substrate films, such as polyester films, which have metal layers, such as aluminum or silver metal, applied thereon through a vacuum deposition or a sputtering process. These supported metal stacks are disclosed in, e.g., U.S. Pat. No. 3,718,535; U.S. Pat. No. 3,816,201; U.S. Pat. No. 3,962,488; U.S. Pat. No. 4,017,661; U.S. Pat. No. 4,166,876; U.S. Pat. No. 4,226,910; U.S. Pat. No. 4,234,654; U.S. Pat. No. 4,368,945; U.S. Pat. No. 4,386,130; U.S. Pat. No. 4,450,201; U.S. Pat. No. 4,465,736; U.S. Pat. No. 4,782,216; U.S. Pat. No. 4,786,783; U.S. Pat. No. 4,799,745; U.S. Pat. No. 4,973,511; U.S. Pat. No. 4,976,503; U.S. Pat. No. 5,024,895; U.S. Pat. No. 5,069,734; U.S. Pat. No. 5,071,206; U.S. Pat. No. 5,073,450; U.S. Pat. No. 5,091,258; U.S. Pat. No. 5,189,551; U.S. Pat. No. 5,264,286; U.S. Pat. No. 5,306,547; U.S. Pat. No. 5,932,329; U.S. Pat. No. 6,391,400; and U.S. Pat. No. 6,455,141. The metallized films are generally disclosed to reflect the appropriate light wavelengths to provide the desired solar control properties. For example, Fujimori, et. al., in U.S. Pat. No. 4,368,945, disclose an infrared reflecting laminated glass for automobile consisting of an infrared reflecting film with tungsten oxide layers between a silver layer sandwiched between poly(vinyl butyral) layers which incorporate ultraviolet absorbents. Brill, et. al., in U.S. Pat. No. 4,450,201, disclose a multilayer heat barrier film. Nishihara, et. al., in U.S. Pat. No. 4,465,736, disclose a laminate with a selective light transmitting film. Woodard, in U.S. Pat. No. 4,782,216 and U.S. Pat. No. 4,786,783, discloses a transparent, laminated window with near infrared rejection which included two transparent conductive metal layers. Farmer, et. al., in U.S. Pat. No. 4,973,511, disclose a laminated solar window construction which includes a PET sheet with a multilayer solar coating. Woodard, in U.S. Pat. No. 4,976,503, discloses an optical element for a motor vehicle windshield which includes light-reflecting metal layers. Hood, et. al., in U.S. Pat. No. 5,071,206, disclose reflecting interference films. Moran, in U.S. Pat. No. 5,091,258, discloses a laminate which incorporates an infra-red radiation reflecting interlayer. Frost, et. al., in U.S. Pat. No. 5,932,329, disclose a laminated glass pane comprising a transparent support film of a tear-resistant polymer provided with an infrared-reflecting coating and two adhesive layer. Woodard, et. al., in U.S. Pat. No. 6,204,480, disclose thin film conductive sheets for automobile windows. Russell, et. al., in U.S. Pat. No. 6,391,400, disclose dielectric layer interference effect thermal control glazings for windows. Woodard, et. al., in U.S. Pat. No. 6,455,141, disclose a laminated glass that incorporates an interlayer carrying an energy-reflective coating. Kramling, et. al., in EP 0 418 123 B1, disclose laminated glass with an interlayer comprising a copolymer of vinyl chloride and glycidyl methacrylate with a plasticizer content of 10 to 40 wt % or a thermoplastic polyurethane. The interlayer may be coated with a reflecting film and the reflecting film may have a surface resistivity of between 2 and 6 Ohms per square. Longmeadow, in U.S. Pat. No. 7,157,133, discloses embossed reflective laminates.
Laminated glass products are capable of providing even more useful properties beyond the safety, display, and solar control characteristics described above. One area of need is for the automotive windshield to function as an acoustic barrier to reduce the level of noise intrusion into the automobile. Acoustic laminated glass is generally known within the art. For example, Asahina, et. al., in U.S. Pat. No. 5,190,826, disclose a sound-insulating interlayer for glass laminates, the interlayer in the form of a laminated film comprising at least one resin film of a poly(vinyl acetal) having a degree of acetalization of at least 50% prepared from an aldehyde having 6 to 10 carbon atoms and a plasticizer and at least one resin film of a poly(vinyl acetal) having a degree of acetalization of at least 50% prepared from an aldehyde having 1 to 4 carbon atoms and a plasticizer or the interlayer in the form of a laminated film comprising a mixture of a poly(vinyl acetal) having a degree of acetalization of at least 50% prepared from an aldehyde having 6 to 10 carbon atoms, a poly(vinyl acetal) having a degree of acetalization of at least 50% prepared from an aldehyde having 1 to 4 carbon atoms and a plasticizer. Ueda, et. al., in U.S. Pat. No. 5,340,654, disclose a sound-insulating interlayer for glass laminates comprising laminated layers of at least one layer which comprises a plasticizer and a poly(vinyl acetal) resin which has 4 to 6 carbon atoms in the acetal group and the average amount of ethylene groups bonded to acetyl groups is 8 to 30 mole % and of at least one layer which comprises a plasticizer and a poly(vinyl acetal) resin which has 3 to 4 carbon atoms in the acetal group and the average amount of ethylene groups bonded to acetyl groups is 4 mole % or less. Rehfeld, et. al., in U.S. Pat. No. 5,368,917 and U.S. Pat. No. 5,478,615, disclose acoustic laminated glazings for vehicles comprising conventional poly(vinyl butyral). The sound damping properties of the poly(vinyl butyral) laminate described therein is highly temperature dependent. Melancon, et. al., in U.S. Pat. No. 5,464,659, disclose radiation curable silicone/acrylate vibration damping articles. Rehfeld, in U.S. Pat. No. 5,773,102, discloses multilayer acoustic laminates comprising a non-acoustic layer and an acoustic layer, wherein the acoustic layer may be composed of certain plasticized terpoly(vinyl chloride-co-glycidyl methacrylate-co-ethylene) materials. Hornsey, in U.S. Pat. No. 5,965,853, discloses a vibration dampening sound absorbing aircraft transparency. Garnier, et. al., in U.S. Pat. No. 6,074,732, disclose a soundproofing laminated window made of two glass sheets with a PVB/PET/acrylate/PET/PVB interlayer. Benson, Jr., et. al., in U.S. Pat. No. 6,119,807, disclose sound dampening glazing which includes a sheet of a sound dampening material. Landin, et. al., in U.S. Pat. No. 6,132,882, disclose acoustic glass laminates which incorporate certain acrylate acoustic layers. Friedman, et. al., in U.S. Pat. No. 6,432,522, disclose an acoustical barrier glazing which includes a multilayer interlayer. Yuan, et. al., in U.S. Pat. No. 6,825,255, disclose certain plasticized poly(vinyl butyral) sheets which include a fatty acid amide. Keller, et. al., in U.S. Pat. No. 6,887,577, disclose acoustic glass laminates which incorporate an acoustic layer of a plasticized poly(vinyl butyral) which includes 50 to 80 wt % of a poly(vinyl butyral) and 20 to 50 wt % of a softener mixture. Bennison, et. al., in US 2006/0008648, disclose a glass laminate interlayer having sound-damping properties comprising a poly(vinyl butyral) resin having a hydroxyl number in the range of from 17 to 23 and 40 to 50 parts per hundred of a single plasticizer.
Accordingly, described herein are durable and safe glass laminates with improved sound damping and solar control properties.